Apparatus for observing the oscillations of light-beams.



No. 815,831. 1 PATENTED MAR. 20, 1906. A. W. HORNAUER.

APPARATUS FOR OBSERVING THE OSGILLATIONS OF LIGHT BEAMS.

APPLICATION FILED MAY13, 1904.

A A l 351 arr UNITED. STATES PATENT OFFICE.

ANDREAS "WILHELM HORNAU'ER, OF CHARLOTTENBURG, GERMANY. I APPARATUS FOR OBSEIRVIING THE OSCILLATIONS OF LlGHT-BEAM S.

Specification of Letters Patent.

Application filed May 13, 1904- Serial No. 207,807-

Patented March 20, 1906.

To all whom it may concern:

Be it known that I, ANDREAS WILHELM HORNAUER, engineer, a subject of the Kin of Bavaria, residing at 15 Cauerstrasse,Ohar ottenburg, near Berlin, Germany, have invented a certainnew and useful Improvement inApparatus for Observing the Oscillations of Light-beams, of which the following is a full, clear, concise, and exact description.

This invention relates to an apparatus for observing the oscillations of light-beams, especially quick oscillations, which in consequence of their rapidity cannot be immediately followed up with'ithe eye. Such oscillations may occur, for instance, in a beam of light from the reflecting-mirror of a measurin instrument, such as a galvanometer, in ta 'ng up the curves of current of electriclight circuits. Oscillations of the said charactcr are usually recorded as functions of the time by employing movablesurfaces to which is imparted a definite velocity at right angle to the plane of oscillation. cylinder-surface has been proposed the axis of which is situatedin the plane of oscillation of the light-beam and which is provided with sensitive paper to record the oscillations as functions of the time. Owing to their lasting efiect, the oscillations of the light-beam are reproduced to the eye as straight lines on the cylinder-surface parallel to its axis. Sometimes it is desirable to render the periodic oscillations directly visible in order to avoid the troublesome photographic process and to makeit possible to alter the oscillations while observin 'them. I attain these objects by the peculiar feature of'the cylindricalbody hereinafter described, and illustrated in the accompanying drawings, in which- Figure 1 is a perspective view of the a paratus. Fig. 2 1s a orizontal section 0 the c lindrical body at right an le to the axis t ereof; Fig. 3, a top vlew of t e same.

In the drawings, w indicates the rotating roller; Z, the source of light; 0, a collectorlens; 8, the oscillating mirror, which is pro-' vided for the oscillating system of the galvanometer g.

Let us suppose in this case that the apparatus serves for taking up the curves of electric-light currents. The roller w, which may be operated by a cord from an electric motor of known frequency, receives the light-ray from the mirror 8, which is set in motion by. the vibrations of the current to be examined For instance, a

dinarily coincides with the axle of rotation a;

but the relative positions may be varied according to circumstances. If the cylindrical body is at rest, the oscillating light will obviously make visible a luminous line on that portion of the cylindrical surface which is struck by the beam. Now the cross-section of the cylindrical body is not confined by a circle concentric to the axis, but has, say, a splral form. In consequence thereof the llghtlng-polnt 1), produced by the fixed lightbeam on the rotating surface, will appear to the observer as moving to and fro at a right angle to the axis of rotation, as shown in Fig. 2, Where the dotted lines indicate different positions of the cylindrical body. The law of this periodic motion of the point p at right angle to the rotating axis obviously depends on the angular velocity and on the shape of cross-section of the said cylindrical body. If, for instance, the angular velocity is uniform and the sections of the cylindrical body are confined by Archimedean spirals, as shown in Fig. 2 of the drawings, the apparent motion of oint p will be to the left with a uniform ve ocity. If now both motions perpendicular to each other of the spot of light on.

on the rotating surface. By suitably ch00s.

ing the given relations curves may be obtalned which will be appropriate to the varying experimental conditions as far as their form and position is concerned. The cylin drical body will therefore not always have a purely cylindrical or developable surface.

The form and area of the sections will, on the contrary, mostly be defined by another law. What I claim as my invention, and desire to secure by Letters Patent, is

In an apparatus for observing the oscillations of light-beams, the combination with In witness whereof I hereunto subscribe an oscillatable mirror reflecting the beam, of my name this 25th day of April, A. D1904.

a cylindrical body revolving at a right angle to the plane of oscillation, said body having ANDREAS WHHELM HORNAUER' 5 cross-sections which are difierent from circles Witnesses: f

concentric with the axis of rotation, as and WOLDEMAR HAUPT,

for the purpose set forth. 7 HENRY HASPER. 

